Abstract PD6-05: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Kehm RD, Phillips K-A, Daly MB, Andrulis IL, Liao Y, Ma X, Zeinomar N, MacInnis RJ, Dite GS, John EM, Buys SS, Milne RL, Hopper JL, Terry MB. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD6-05.

Abstract P4-09-02: Validation of iPrevent using the prospective family study cohort (ProF-SC)

Background: iPrevent (https://www.petermac.org/iprevent) provides women with highly-tailored risk management information after first estimating their breast cancer (BC) risk using the established risk prediction models, IBIS and BOADICEA. iPrevent has an internal switching algorithm that governs which model is used for each woman, depending on her risk factor data (i.e. LCIS/atypical hyperplasia status, BRCA status, and cancer family history). This study assessed the calibration and discriminatory accuracy of the 10-year BC risk estimates provided by iPrevent. Methods: Subjects were 16,574 women in the ProF-SC, aged 18-70 years and without BC or bilateral mastectomy at recruitment. After 10 years follow-up, 655 women (4%) were diagnosed with invasive BC. A “batch mode” for iPrevent is not available, so the iPrevent-assigned cumulative 10-year invasive BC risks were calculated by entering self-reported risk factors at cohort entry into either the IBIS (10,169 women) or BOADICEA (6,405 women) software packages (according to the iPrevent switching algorithm). To assess calibration, the mean iPrevent-assigned risk was compared with the mean 10-year observed invasive BC incidence, using a chi-squared goodness-of-fit statistic for the whole cohort, and by quartiles of risk. To evaluate discriminatory accuracy, the overall area under the receiver operating characteristic curve (AUC) for the development of invasive BC within 10 years was computed. Data were censored at date of invasive or in situ BC diagnosis, bilateral mastectomy, death, loss to follow-up, or at 10 years of follow-up. Results: For the whole cohort, iPrevent assigned risk was well-calibrated – 690 expected BCs (E) 655 observed (O) (E/O=1.05, 95% CI: 0.98-1.14), although for women in the highest risk quartile, i.e. >6% 10-year risk, E/O=1.19, 95% CI: 1.07-1.32. The AUC was 0.70, 95% CI: 0.68-0.72. Conclusions: iPrevent is well calibrated overall and has good discriminatory accuracy for predicting 10-year BC risk, thus justifying its clinical use.

Citation Format: Phillips K-A, Liao Y, Collins IM, Buchsbaum R, Weideman P, Bickerstaffe A, MacInnis RJ, kConFab Investigators, Cuzick J, Antoniou A, Andrulis IL, John EM, Daly MB, Buys SS, Hopper JL, Terry MB. Validation of iPrevent using the prospective family study cohort (ProF-SC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-09-02.

Abstract P6-09-04: Benign breast disease and breast cancer risk across the spectrum of familial risk using a prospective family study cohort (ProF-SC)

Background: Benign breast disease (BBD) is one of the strongest risk factors for breast cancer but it is unclear whether the strength of the association with BBD and breast cancers varies by breast cancer family history. Few studies of BBD enrich specifically for putative genetic factors by over-sampling based on family history let alone evaluate potential interactions with measures of underlying familial risk. The aim of this study was to evaluate how risk associated with BBD is modified by underlying familial risk so as to guide clinical management and risk assessment of women with BBD.

Methods: Using a prospective family study cohort of 17,154 women unaffected with breast cancer at baseline and followed by questionnaire at regular intervals, we examined the association between BBD and breast cancer risk using Cox Proportional Hazards models. We classified women as having BBD if they reported at baseline having been told by a doctor that they had BBD, such as a non-cancerous cyst or breast lump. We did not have information on histologic sub-type. We confirmed self-reported diagnosis of BBD with pathology reports in a subset of the New York cohort and found high agreement between self-reported and pathologically confirmed BBD (93.5%). We assessed multiplicative and additive interactions with underlying familial risk profile (FRP) defined as either fixed-time horizon of 1-year, or total lifetime risk, estimated from the Breast Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA) model.

Results: During 176,756 person-years of follow-up (mean 10.2, maximum 23.7 years), we observed 968 incident breast cancers cases with an average age at diagnosis of 55.8 years and average age at enrollment into the cohort of 46.8 years. At baseline, 4,704 (27%) women reported having a previous diagnosis of BBD. Compared to women with no history of BBD, breast cancer risk was increased in women of all ages (HR: 1.37, 95% CI: 1.19,1.56), and in women up to age 45 years (using attained age models) (HR: 1.40, 95% CI: 1.01,1.93). In terms of recency of BBD, we found that the increased risk associated with BBD remained 21 years or more after the initial BBD diagnosis (HR: 1.37, 95% CI: 1.11, 1.68). We found no evidence for multiplicative interactions with FRP, which implies that the increase in absolute risk associated with BBD depends on a woman's FRP (Table 1).

Conclusions: Women with a history of BBD have an increased risk of breast cancer that multiplies their underlying familial risk (FRP). These results could prove to be valuable for risk counseling and clinical management.

Table 1: Cumulative Incidence of Breast Cancer to age 45, 55, and 65 by BBD and underlying FRP as measured by 10-year BOADICEA score.AgeNo BBD, <3.4 %BBD, <3.4%No BBD, ≥3.4%BBD, ≥3.4%454.6 (3.8, 5.6)6.1(4.7, 8.0)12.1 (10.2, 14.5)16.1 (13.1, 19.7)557.4 (6.3, 8.7)9.8 (7.5, 12.8)19.1 (16.6, 22.0)25.0 (21.7, 28.9)659.7 (8.2, 11.5)12.8 (9.9, 16.5)24.5 (21.8, 27.6)31.8 (28.3, 35.7)

Citation Format: Zeinomar N, Phillips KA, Liao Y, MacInnis RJ, Dite GS, Daly MB, John EM, Andrulis IL, Buys SS, Hopper JL, Terry MB. Benign breast disease and breast cancer risk across the spectrum of familial risk using a prospective family study cohort (ProF-SC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-09-04.

Abstract P6-09-01: Risk-reducing oophorectomy and breast cancer risk across the spectrum of familial risk using a prospective family study cohort (ProF-SC)

Background: Whether risk-reducing salpingo oophorectomy (RRSO) reduces breast cancer risk in addition to reducing ovarian cancer risk is controversial with some arguing that the previous evidence of a reduction in breast cancer risk from RRSO was due to bias. Evidence from independent prospective cohorts of high-risk women is needed to resolve this controversy.

Methods: Using a prospective family study cohort of 17,810 women unaffected with breast cancer at baseline, we examined the association between RRSO and breast cancer risk using Cox Proportional Hazards models. We compared results estimating RRSO as a non-time-dependent variable to results treating RRSO as a time-dependent variable, because failing to account for the time-varying nature of a covariate person- time prior to RRSO, should it exist, will incorrectly attribute the cancer-free person-time to RRSO. We separately examined the association with RRSO in BRCA1 and BRCA2 mutation carriers and non-carriers, and further performed gene-stratified analyses in women with BRCA1 and BRCA2 only. We also assessed multiplicative interactions with underlying familial risk profile (FRP), defined as total lifetime risk estimated from the Breast Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA) model.

Results: During a median 10.7 years of follow-up (maximum 23.7 years), we observed 1,040 incident cases of breast cancer with an average age at diagnosis of 55.8 years and average age at enrollment into the cohort of 46.8 years. A total of 2434 (14%) women reported at baseline having a RRSO. We observed decreased risk of breast cancer associated with RRSO for both BRCA1(N= 650) and BRCA2(N=557) mutation carriers when RRSO was treated as a fixed covariate (HR= 0.60, 95% CI=0.40-0.92 and HR= 0.40, 95%CI = 0.23-0.69, respectively). In contrast, when we treated RRSO as a time-varying covariate, for both BRCA1 and BRCA2 carriers, we no longer observed a decreased risk for BRCA1 and BRCA2 carriers (HR= 1.67, 95% CI=1.05-2.67 and HR= 0.97, 95%CI = 0.53-1.80, respectively). There was no association between RRSO and breast cancer risk for non-carriers (N=16,603), whether we treated RRSO as a fixed or time varying covariate (HR= 0.88, 95% CI=0.72-1.08 and HR= 1.06, 95%CI = 0.85-1.30, respectively).

Conclusions: Our findings provide an independent replication that the reduced risk of breast cancer previously observed in BRCA1 and BRCA2 mutation carrier women may be from bias in counting person-time. Clinical management of high-risk women should counsel based on the reduced risk of ovarian cancer from RRSO, but not breast cancer.

Citation Format: Terry MB, Phillips KA, Daly MB, Andrulis IL, Liao Y, Ma X, Zeinomar N, MacInnis RJ, Dite GS, John EM, Buys SS, Hopper JL. Risk-reducing oophorectomy and breast cancer risk across the spectrum of familial risk using a prospective family study cohort (ProF-SC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-09-01.

Abstract P2-06-01: Non-genetic risk factors improve accuracy of breast cancer risk assessment for women at high familial risk: Comparison of risk estimation models using the prospective family study cohort (ProF-SC)

This abstract was withdrawn by the authors.

Abstract P5-08-05: Prospective family cohort analyses of gene-environment interactions in breast cancer: Body mass index

This abstract was not presented at the symposium.

Association of lifestyle and demographic factors with estrogenic and glucocorticogenic activity in Mexican American women

Breast cancer risk is higher in US-born than in foreign-born Hispanics/Latinas and also increases with greater length of US residency. It is only partially known what factors contribute to these patterns of risk. To gain new insights, we tested the association between lifestyle and demographic variables and breast cancer status, with measures of estrogenic (E) and glucocorticogenic (G) activity in Mexican American women. We used Chemical-Activated LUciferase gene eXpression assays to measure E and G activity in total plasma from 90 Mexican American women, without a history of breast cancer at the time of recruitment, from the San Francisco Bay Area Breast Cancer Study. We tested associations of nativity, lifestyle and sociodemographic factors with E and G activity using linear regression models. We did not find a statistically significant difference in E or G activity by nativity. However, in multivariable models, E activity was associated with Indigenous American ancestry (19% decrease in E activity per 10% increase in ancestry, P = 0.014) and with length of US residency (28% increase in E activity for every 10 years, P = 0.035). G activity was associated with breast cancer status (women who have developed breast cancer since recruitment into the study had 21% lower G activity than those who have not, P = 0.054) and alcohol intake (drinkers had 25% higher G activity than non-drinkers, P = 0.015). These associations suggest that previously reported breast cancer risk factors such as genetic ancestry and alcohol intake might in part be associated with breast cancer risk through mechanisms linked to the endocrine system.

Multigene testing of moderate-risk genes: be mindful of the missense

BACKGROUND

Moderate-risk genes have not been extensively studied, and missense substitutions in them are generally returned to patients as variants of uncertain significance lacking clearly defined risk estimates. The fraction of early-onset breast cancer cases carrying moderate-risk genotypes and quantitative methods for flagging variants for further analysis have not been established.

METHODS

We evaluated rare missense substitutions identified from a mutation screen of ATM, CHEK2, MRE11A, RAD50, NBN, RAD51, RINT1, XRCC2 and BARD1 in 1297 cases of early-onset breast cancer and 1121 controls via scores from Align-Grantham Variation Grantham Deviation (GVGD), combined annotation dependent depletion (CADD), multivariate analysis of protein polymorphism (MAPP) and PolyPhen-2. We also evaluated subjects by polygenotype from 18 breast cancer risk SNPs. From these analyses, we estimated the fraction of cases and controls that reach a breast cancer OR≥2.5 threshold.

RESULTS

Analysis of mutation screening data from the nine genes revealed that 7.5% of cases and 2.4% of controls were carriers of at least one rare variant with an average OR≥2.5. 2.1% of cases and 1.2% of controls had a polygenotype with an average OR≥2.5.

CONCLUSIONS

Among early-onset breast cancer cases, 9.6% had a genotype associated with an increased risk sufficient to affect clinical management recommendations. Over two-thirds of variants conferring this level of risk were rare missense substitutions in moderate-risk genes. Placement in the estimated OR≥2.5 group by at least two of these missense analysis programs should be used to prioritise variants for further study. Panel testing often creates more heat than light; quantitative approaches to variant prioritisation and classification may facilitate more efficient clinical classification of variants.

Reproductive risk factors and oestrogen/progesterone receptor-negative breast cancer in the Breast Cancer Family Registry

BACKGROUND

Oestrogen receptor (ER)- and progesterone receptor (PR)-negative (ER-PR-) breast cancer is associated with poorer prognosis compared with other breast cancer subtypes. High parity has been associated with an increased risk of ER-PR- cancer, but emerging evidence suggests that breastfeeding may reduce this risk. Whether this potential breastfeeding benefit extends to women at high risk of breast cancer remains critical to understand for prevention.

METHODS

Using population-based ascertained cases (n=4011) and controls (2997) from the Breast Cancer Family Registry, we examined reproductive risk factors in relation to ER and PR status.

RESULTS

High parity (≥3 live births) without breastfeeding was positively associated only with ER-PR- tumours (odds ratio (OR)=1.57, 95% confidence interval (CI), 1.10-2.24); there was no association with parity in women who breastfed (OR=0.93, 95% CI 0.71-1.22). Across all race/ethnicities, associations for ER-PR- cancer were higher among women who did not breastfeed than among women who did. Oral contraceptive (OC) use before 1975 was associated with an increased risk of ER-PR- cancer only (OR=1.32, 95% CI 1.04-1.67). For women who began OC use in 1975 or later there was no increased risk.

CONCLUSIONS

Our findings support that there are modifiable factors for ER-PR- breast cancer and that breastfeeding in particular may mitigate the increased risk of ER-PR- cancers seen from multiparity.

Oral Contraceptive Use and Parity Associations with Uncommon Breast Cancer Histologies in the Breast Cancer Family Registry: the Role of Family History

Purpose: The effect of parity and oral contraceptive (OC) use on breast cancer risk differs by cancer subtype as defined by histology. Family history of breast cancer impacts decisions regarding both parity and oral contraceptive use; it is unknown whether reproductive risk factors are related to uncommon histologies in women with and without a strong family history.

Methods: Using population-based data from the Breast Cancer Family Registry, we conducted analyses using unordered polytomous regression to determine the role of family history in associations between parity, OC use, and breast cancer histologic subtype, among 3,260 cases and 2,997 controls. Histologic types examined included ductal and lobular as well as the uncommon histologies of mucinous, tubular, and medullary cancer.

Results: Twenty-eight percent of cases and 9% of controls had a family history (defined as at least 1 first-degree relative with breast cancer). Cases with and without family history were similar in regards to OC use (75% and 73%, respectively were ever-users) and parity (2.08 children in cases with family history, 2.10 in cases without). In a multivariable model, when compared with controls, OC use was inversely associated with tumors of mucinous histology (OR = 0.43, 95% CI 0.23–0.79 for use ≥5 years vs. never use). There was a stronger inverse association with OC use and the mucinous subtype among those without a family history (OR = 0.27, 95% CI 0.13–0.57), and a nonsignificant positive association in those with family history (OR = 2.19, 95% CI 0.40–11.84). High parity (≥3 children) was positively associated with medullary histology (OR = 2.62, 95% CI 1.16–5.91, compared with nulliparity); the association was stronger among women without a family history (OR = 4.31, 95% CI 1.67–11.12), and was not significantly associated among those with a family history (OR = 0.36, 95% CI 0.06–2.29). Parity was inversely associated with the mucinous type (OR = 0.45, 95% CI 0.21–0.96, compared with nulliparity), and this effect remained stable in women with and without family history.

Conclusion: This study suggests that selected reproductive risk factors may only be related to uncommon breast cancer histologies among women without a family history of breast cancer.

Germline mutations in CDH1 are infrequent in women with early-onset or familial lobular breast cancers

BACKGROUND

Germline mutations in CDH1 are associated with hereditary diffuse gastric cancer; lobular breast cancer also occurs excessively in families with such condition.

METHOD

To determine if CDH1 is a susceptibility gene for lobular breast cancer in women without a family history of diffuse gastric cancer, germline DNA was analysed for the presence of CDH1 mutations in 318 women with lobular breast cancer who were diagnosed before the age of 45 years or had a family history of breast cancer and were not known, or known not, to be carriers of germline mutations in BRCA1 or BRCA2. Cases were ascertained through breast cancer registries and high-risk cancer genetic clinics (Breast Cancer Family Registry, the kConFab and a consortium of breast cancer genetics clinics in the United States and Spain). Additionally, Multiplex Ligation-dependent Probe Amplification was performed for 134 cases to detect large deletions.

RESULTS

No truncating mutations and no large deletions were detected. Six non-synonymous variants were found in seven families. Four (4/318 or 1.3%) are considered to be potentially pathogenic through in vitro and in silico analysis.

CONCLUSION

Potentially pathogenic germline CDH1 mutations in women with early-onset or familial lobular breast cancer are at most infrequent.

Increased cancer risks for relatives of very early-onset breast cancer cases with and without BRCA1 and BRCA2 mutations

Background:

Little is known regarding cancer risks for relatives of women with very early-onset breast cancer.

Methods:

We studied 2208 parents and siblings of 504 unselected population-based Caucasian women with breast cancer diagnosed before age 35 years (103 from USA, 124 from Canada and 277 from Australia), 41 known to carry a mutation (24 in BRCA1, 16 in BRCA2 and one in both genes). Cancer-specific standardised incidence ratios (SIRs) were estimated by comparing the number of affected relatives (50% verified overall) with that expected based on incidences specific for country, sex, age and year of birth.

Results:

For relatives of carriers, the female breast cancer SIRs were 13.13 (95% CI 6.57–26.26) and 12.52 (5.21–30.07) for BRCA1 and BRCA2, respectively. The ovarian cancer SIR was 12.38 (3.1–49.51) for BRCA1 and the prostate cancer SIR was 18.55 (4.64–74.17) for BRCA2. For relatives of non-carriers, the SIRs for female breast, prostate, lung, brain and urinary cancers were 4.03 (2.91–5.93), 5.25 (2.50–11.01), 7.73 (4.74–12.62), 5.19 (2.33–11.54) and 4.35 (1.81–10.46), respectively. For non-carriers, the SIRs remained elevated and were statistically significant for breast and prostate cancer when based on verified cancers.

Conclusion:

First-degree relatives of women with very early-onset breast cancer are at increased risk of cancers not explained by BRCA1 and BRCA2 mutations.

Evaluation of a candidate breast cancer associated SNP in ERCC4 as a risk modifier in BRCA1 and BRCA2 mutation carriers. Results from the Consortium of Investigators of Modifiers of BRCA1/BRCA2 (CIMBA)

Background:

In this study we aimed to evaluate the role of a SNP in intron 1 of the ERCC4 gene (rs744154), previously reported to be associated with a reduced risk of breast cancer in the general population, as a breast cancer risk modifier in BRCA1 and BRCA2 mutation carriers.

Methods:

We have genotyped rs744154 in 9408 BRCA1 and 5632 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) and assessed its association with breast cancer risk using a retrospective weighted cohort approach.

Results:

We found no evidence of association with breast cancer risk for BRCA1 (per-allele HR: 0.98, 95% CI: 0.93–1.04, P=0.5) or BRCA2 (per-allele HR: 0.97, 95% CI: 0.89–1.06, P=0.5) mutation carriers.

Conclusion:

This SNP is not a significant modifier of breast cancer risk for mutation carriers, though weak associations cannot be ruled out.

Prognosis in BRCA1, BRCA2 associated breast cancer (BC): a prospective Breast Cancer Family Registry (BCFR) international population-based cohort study

Abstract #2072

Hereditary BC occurs at a younger age and is associated with more adverse tumor-related features than sporadic breast cancer (BC) (defined here as BC in those with no 1st or 2nd degree family history of breast or ovarian cancer). Using pre-specified criteria, we assembled a population-based cohort of newly diagnosed BC at 3 centers: Ontario, Canada (1996-98), San Francisco Bay area, USA (1995-2000), Melbourne/Sydney, Australia (1991-1998). Medical information was obtained from medical records; women were followed prospectively for recurrence, new cancers and death. Pathology data were obtained from central review or pathology reports. BRCA1 and BRCA2 mutation testing was performed on 77% and 70% of cases, respectively (sporadic BC cases were not tested at 2 centers). Hereditary and sporadic BC cases were compared using Cox proportional hazards (stratified by center). 3215 eligible cases were enrolled in the BCFR, with a mean age at diagnosis of 46.9 years. Median follow-up was 7.61 years; 565 women had distant recurrences and 547 died. There were 92 cases with BRCA1 and 72 with BRCA2 mutations; 1549 (48.2%) had sporadic BC; the remainder had familial BC as defined above. BRCA1 mutations were associated with young age, estrogen and progesterone receptor (ER and PgR) negativity and high grade; BRCA2 mutations were associated with node positivity and high grade. Distant disease-free survival (DDFS) and overall survival (OS) did not differ significantly between BRCA1 carriers and sporadic cases in univariate or multivariate analyses. DDFS and OS were worse in BRCA2 carriers than in sporadic cases (HR 1.6, p=0.04 and HR 1.8, p=0.01, respectively) in univariate analyses but not in multivariate analyses (DDFS HR 1.0, p=0.98; OS HR 1.13, p=0.61). The small group of BRCA2 carriers who did not receive adjuvant chemotherapy had a significantly worse OS (multivariate HR 3.63, p = 0.005). Furthermore, BRCA2 carriers who received adjuvant tamoxifen had significantly worse OS than women with sporadic BC (HR=2.0, p=0.03). We conclude that BRCA1 and BRCA2 mutations do not independently impact DDFS or OS. Significantly worse outcomes were seen in BRCA2 carrier subgroups defined by adjuvant treatment; this requires further investigation and may have implications for clinical practice.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2072.

Validation study of the LAMBDA model for predicting the BRCA1 or BRCA2 mutation carrier status of North American Ashkenazi Jewish women

LAMBDA is a model that estimates the probability an Ashkenazi Jewish (AJ) woman carries an ancestral BRCA1 or BRCA2 mutation from her personal and family cancer history. LAMBDA is relevant to clinical practice, and its implementation does not require a computer. It was developed principally from Australian and UK data. We conducted a validation study using 1286 North American AJ women tested for the mutations 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2. Most had a personal or family history of breast cancer. We observed 197 carriers. The area under the receiver operator characteristic (ROC) curve (a measure of ranking) was 0.79 [95% confidence interval (CI) = 0.77-0.81], similar to that for the model-generating data (0.78; 95% CI = 0.75-0.82). LAMBDA predicted 232 carriers (18% more than observed; p = 0.002) and was overdispersed (p = 0.009). The Bayesian computer program BRCAPRO gave a similar area under the ROC curve (0.78; 95% CI = 0.76-0.80), but predicted 367 carriers (86% more than observed; p < 0.0001), and was substantially overdispersed (p < 0.0001). Therefore, LAMBDA is comparable to BRCAPRO for ranking AJ women according to their probability of being a BRCA1 or BRCA2 mutation carrier and is more accurate than brcapro which substantially overpredicts carriers in this population.

Population-based estimates of breast cancer risks associated with ATM gene variants c.7271T>G and c.1066-6T>G (IVS10-6T>G) from the Breast Cancer Family Registry

The ATM gene variants segregating in ataxia-telangiectasia families are associated with increased breast cancer risk, but the contribution of specific variants has been difficult to estimate. Previous small studies suggested two functional variants, c.7271T>G and c.1066-6T>G (IVS10-6T>G), are associated with increased risk. Using population-based blood samples we found that 7 out of 3,743 breast cancer cases (0.2%) and 0 out of 1,268 controls were heterozygous for the c.7271T>G allele (P=0.1). In cases, this allele was more prevalent in women with an affected mother (odds ratio [OR]=5.5, 95% confidence interval [CI]=1.2-25.5; P=0.04) and delayed child-bearing (OR=5.1; 95% CI=1.0-25.6; P=0.05). The estimated cumulative breast cancer risk to age 70 years (penetrance) was 52% (95% CI=28-80%; hazard ratio [HR]=8.6; 95% CI=3.9-18.9; P<0.0001). In contrast, 13 of 3,757 breast cancer cases (0.3%) and 10 of 1,268 controls (0.8%) were heterozygous for the c.1066-6T>G allele (OR=0.4; 95% CI=0.2-1.0; P=0.05), and the penetrance was not increased (P=0.5). These findings suggest that although the more common c.1066-6T>G variant is not associated with breast cancer, the rare ATM c.7271T>G variant is associated with a substantially elevated risk. Since c.7271T>G is only one of many rare ATM variants predicted to have deleterious consequences on protein function, an effective means of identifying and grouping these variants is essential to assess the contribution of ATM variants to individual risk and to the incidence of breast cancer in the population.

The role of self-defined race/ethnicity in population structure control

Population-based association studies are powerful tools for the genetic mapping of complex diseases. However, this method is sensitive to potential confounding by population structure. While statistical methods that use genetic markers to detect and control for population structure have been the focus of current literature, the utility of self-defined race/ethnicity in controlling for population structure has been controversial. In this study of 1334 individuals, who self-identified as either African American, European American or Hispanic, we demonstrated that when the true underlying genetic structure and the self-defined racial/ethnic groups were roughly in agreement with each other, the self-defined race/ethnicity information was useful in the control of population structure.

Relation of contraceptive and reproductive history to ovarian cancer risk in carriers and noncarriers of BRCA1 gene mutations

In the general population, ovarian cancer risk is inversely associated with oral contraceptive use, tubal ligation, and childbearing. Among carriers of BRCA1 gene mutations, the data are conflicting. The authors identified women diagnosed with incident invasive epithelial ovarian cancer in the San Francisco Bay Area of California from March 1997 through July 2001. They compared the contraceptive and reproductive histories of 36 carrier cases and 381 noncarrier cases with those of 568 controls identified by random digit dialing who were frequency matched to cases on age and race/ethnicity. In both carriers and noncarriers, reduced risk was associated with ever use of oral contraceptives (odds ratio = 0.54 (95% confidence interval (CI): 0.26, 1.13) for carriers and 0.55 (95% CI: 0.41, 0.73) for noncarriers), duration of oral contraceptive use (risk reduction per year = 13% (p = 0.01) for carriers and 6% (p < 0.001) for noncarriers), history of tubal ligation (odds ratio = 0.68 (95% CI: 0.25, 1.90) for carriers and 0.65 (95% CI: 0.45, 0.95) for noncarriers), and increasing parity (risk reduction per childbirth = 16% (p = 0.26) for carriers and 24% (p < 0.001) for noncarriers). These data suggest that BRCA1 mutation carriers and noncarriers have similar risk reductions associated with oral contraceptive use, tubal ligation, and parity.

Phytoestrogen consumption and breast cancer risk in a multiethnic population: the Bay Area Breast Cancer Study

Research on the relation between phytoestrogens and breast cancer risk has been limited in scope. Most epidemiologic studies have involved Asian women and have examined the effects of traditional soy foods (e.g., tofu), soy protein, or urinary excretion of phytoestrogens. The present study extends this research by examining the effects of a spectrum of phytoestrogenic compounds on breast cancer risk in non-Asian US women. African-American, Latina, and White women aged 35-79 years, who were diagnosed with breast cancer between 1995 and 1998, were compared with women selected from the general population via random digit dialing. Interviews were conducted with 1,326 cases and 1,657 controls. Usual intake of specific phytoestrogenic compounds was assessed via a food frequency questionnaire and a newly developed nutrient database. Phytoestrogen intake was not associated with breast cancer risk (odds ratio = 1.0, 95% confidence interval: 0.80, 1.3 for the highest vs. lowest quartile). Results were similar for pre- and postmenopausal women, for women in each ethnic group, and for all seven phytoestrogenic compounds studied. Phytoestrogens appear to have little effect on breast cancer risk at the levels commonly consumed by non-Asian US women: an average intake equivalent to less than one serving of tofu per week.

Lifestyle determinants of 5alpha-reductase metabolites in older African-American, white, and Asian-American men

Men with higher endogenous 5alpha-reductase activity may have higher prostate cancer risk. This hypothesis raises two questions: (a) Could racial differences in 5alpha-reductase activity explain the observed racial differences in prostate cancer risk? and (b) Could a man reduce his activity level by modifying his lifestyle? To address these questions, we measured two hormonal indices of 5alpha-reductase activity [serum levels of androstane-3alpha-17beta-diol glucuronide (3alpha-diol G) and androsterone glucuronide (AG)] in healthy, older African-American, white, and Asian-American men, who are at high, intermediate, and low prostate cancer risk, respectively. We also examined associations between these metabolite levels and such lifestyle characteristics as body size and physical activity as well as select aspects of medical history and family history of prostate cancer. Men included in this cross-sectional analysis (n = 1054) had served as control subjects in a population-based case-control study of prostate cancer we conducted in California, Hawaii, and Vancouver, Canada and provided information on certain personal attributes and donated blood between March 1990 and March 1992. In this study, concentrations of 3alpha-diol G declined significantly with age and increased significantly with body mass index. Mean levels of 3alpha-diol G, adjusted for age and body mass index, were 6.1 ng/ml in African-Americans, 6.9 ng/ml in whites and 4.8 ng/ml in Asian-Americans. These differences were statistically significant (African-Americans versus whites: P < 0.01; whites versus Asian-Americans: P < 0.001). Concentrations of AG decreased significantly with age, but only in whites, and were unrelated to any of the reported personal attributes. Mean levels of AG, adjusted for age, were 44.1 ng/ml in African-Americans, 44.9 ng/ml in whites, and 37.5 ng/ml in Asian-Americans (Asian-Americans versus whites, P < 0.001). In conclusion, older African-American and white men have similar levels of these two indices of 5alpha-reductase activity, and these levels are higher than those of older Asian-American men. This difference may be related to the lower prostate cancer risk in Asian-Americans.

Vegetables, fruits, legumes and prostate cancer: a multiethnic case-control study

The evidence for a protective effect of vegetables, fruits, and legumes against prostate cancer is weak and inconsistent. We examined the relationship of these food groups and their constituent foods to prostate cancer risk in a multicenter case-control study of African-American, white, Japanese, and Chinese men. Cases (n = 1619) with histologically confirmed prostate cancer were identified through the population-based tumor registries of Hawaii, San Francisco, and Los Angeles in the United States and British Columbia and Ontario in Canada. Controls (n = 1618) were frequency-matched to cases on ethnicity, age, and region of residence of the case, in a ratio of approximately 1:1. Dietary and other information was collected by in-person home interview; a blood sample was obtained from control subjects for prostate-specific antigen determination. Odds ratios (OR) were estimated using logistic regression, adjusting for age, geographic location, education, calories, and when indicated, ethnicity. Intake of legumes (whether total legumes, soyfoods specifically, or other legumes) was inversely related to prostate cancer (OR for highest relative to lowest quintile for total legumes = 0.62; P for trend = 0.0002); results were similar when restricted to prostate-specific antigen-normal controls or to advanced cases. Intakes of yellow-orange and cruciferous vegetables were also inversely related to prostate cancer, especially for advanced cases, among whom the highest quintile OR for yellow-orange vegetables = 0.67 (P for trend = 0.01) and the highest quintile OR for cruciferous vegetables = 0.61 (P for trend = 0.006). Intake of tomatoes and of fruits was not related to risk. Findings were generally consistent across ethnic groups. These results suggest that legumes (not limited to soy products) and certain categories of vegetables may protect against prostate cancer.

Sources of phytoestrogen exposure among non-Asian women in California, USA

OBJECTIVE

We recently described the development of a comprehensive database for assessing phytoestrogen exposure in epidemiologic studies. This paper describes the first application of this database and the primary sources of phytoestrogen consumption in non-Asian women.

METHODS

Four hundred and forty-seven randomly selected African-American, Latina, and white women, ages 50-79 years, residing in California's San Francisco Bay Area and participating as controls in an ongoing population-based case-control study of breast cancer, were included in the present analysis. Average daily consumption of each of seven phytoestrogenic compounds was determined for each woman by combining the values from the new database with food consumption reported on a food-frequency questionnaire.

RESULTS

Phytoestrogens in the non-Asian Bay Area diet appear to come primarily from: (1) traditional soy-based foods (e.g. tofu and soy milk); (2) "hidden" sources of soy (e.g. foods containing added soy protein isolate, soy concentrate, or soy flour, e.g. many brands of doughnuts and white bread); and (3) a variety of foods which contain only low to moderate amounts of phytoestrogens per 100 grams but which are frequently consumed (e.g. coffee and orange juice).

CONCLUSIONS

In the absence of a comprehensive assessment of various phytoestrogens in a wide variety of foods, epidemiologic studies could suffer from the effects of uncontrolled confounding by unmeasured sources of phytoestrogen exposure potentially leading to biased estimates of effect and misinterpretation of findings.

Assessing phytoestrogen exposure in epidemiologic studies: development of a database (United States)

BACKGROUND AND OBJECTIVE

Phytoestrogens (weak estrogens found in plants or derived from plant precursors by human metabolism) have been hypothesized to reduce the risk of a number of cancers. However, epidemiologic studies addressing this issue are hampered by the lack of a comprehensive phytoestrogen database for quantifying exposure. The purpose of this research was to develop such a database for use with food-frequency questionnaires in large epidemiologic studies.

METHODS

The database is based on consumption patterns derived from semistructured interviews with 118 African-American, Latina, and white women residing in California's San Francisco Bay Area. HPLC-mass spectrometry was used to determine the content of seven specific phytoestrogenic compounds (i.e. the isoflavones: genistein, daidzein, biochanin A, and formononetin; the coumestan: coumestrol; and the plant lignans: matairesinol and secoisolariciresinol) in each of 112 food items/groups.

RESULTS

Traditional soy-based foods were found to contain high levels of genistein and daidzein, as expected, as well as substantial amounts of coumestrol. A wide variety of "hidden" sources of soy (that is, soy protein isolate, soy concentrate, or soy flour added to foods) was observed. Several other foods (such as various types of sprouts and dried fruits, garbanzo beans, asparagus, garlic, and licorice) were also found to be substantial contributors of one or more of the phytoestrogens analyzed.

CONCLUSIONS

Databases, such as the one described here, are important in assessing the relationship between phytoestrogen exposure and cancer risk in epidemiologic studies. Agencies, such as the United States Department of Agriculture (USDA), that routinely provide data on food composition, on which epidemiologic investigations into dietary health effects are based, should consider instituting programs for the analysis of phytochemicals, including the phytoestrogens.

Vitamin D and breast cancer risk: the NHANES I Epidemiologic follow-up study, 1971-1975 to 1992. National Health and Nutrition Examination Survey

We analyzed data from the first National Health and Nutrition Examination Survey Epidemiologic Follow-up Study to test the hypothesis that vitamin D from sunlight exposure, diet, and supplements reduces the risk of breast cancer. We identified 190 women with incident breast cancer from a cohort of 5009 white women who completed the dermatological examination and 24-h dietary recall conducted from 1971-1974 and who were followed up to 1992. Using Cox proportional hazards regression, we estimated relative risks (RRs) for breast cancer and 95% confidence intervals, adjusting for age, education, age at menarche, age at menopause, body mass index, alcohol consumption, and physical activity. Several measures of sunlight exposure and dietary vitamin D intake were associated with reduced risk of breast cancer, with RRs ranging from 0.67-0.85. The associations with vitamin D exposures, however, varied by region of residence. The risk reductions were highest for women who lived in United States regions of high solar radiation, with RRs ranging from 0.35-0.75. No reductions in risk were found for women who lived in regions of low solar radiation. Although limited by the relatively small size of the case population, the protective effects of vitamin D observed in this prospective study are consistent for several independent measures of vitamin D. These data support the hypothesis that sunlight and dietary vitamin D reduce the risk of breast cancer.

Recreational and occupational physical activities and risk of breast cancer

Physical activity has been hypothesized to reduce breast cancer risk, but an inverse association has not been consistently reported. In this review, we critically evaluate for coherence, validity, and bias the epidemiologic studies on recreational or occupational physical activity, discuss the biologic plausibility of the association, and identify areas for future research. Results from seven of nine studies suggest that higher levels of occupational physical activity may be associated with a reduction in risk, at least among a subgroup of women. Eleven of 16 investigations on recreational exercise reported a 12%-60% decrease in risk among premenopausal and postmenopausal women, although a dose-response trend was not evident in most of the studies. The reduction in risk associated with exercise was more likely to be observed in case-control studies than in cohort studies. Most investigations incompletely assessed physical activity, which contributed to conflicting findings on the optimal time period, duration, frequency, or intensity of activity to minimize risk. Physical activity may exert its effects through changes in menstrual characteristics, reduced body size, or alterations in immune function. In summary, most epidemiologic studies of physical activity reported a reduction in the risk of breast cancer among physically active women. Future research studies should focus on using a cohort design to rule out recall bias as a possible explanation for the decrease in risk associated with exercise, on improving assessment of lifetime physical activity from all sources to clarify whether there is a dose-response relation or an optimal time period, duration, frequency, or intensity of activity, and on elucidating the underlying mechanisms for the inverse association.

Serum levels of prostate-specific antigen among Japanese-American and native Japanese men

BACKGROUND

Fourfold to sixfold higher prostate cancer rates in Japanese-American men in the United States compared with Japanese men in Japan have been cited to support a role for environmental risk factors in the etiology of the disease. To examine the hypothesis that part or all of the elevated prostate cancer rates in Japanese-American men may reflect more intensive prostate cancer screening in the United States than in Japan, we compared prostate-specific antigen (PSA) levels in community-based samples of serum from men without prostate cancer.

METHODS

Japanese-American men aged 40-85 years and native Japanese men aged 40-89 years with no history of prostate cancer provided sera, respectively, in the United States from March 1990 through March 1992 (n = 237) or in Japan from January 1992 through December 1993 (n = 3522). Age-specific PSA levels were used to estimate the prevalences of undetected prostate cancer in the two populations.

RESULTS

Age-specific mean PSA levels were significantly lower in Japanese-Americans than in native Japanese (two-sided P<.001). The prevalence of an elevated PSA level increased with age in both populations and exceeded 5% among men aged 60 years or more. Combined with data on prevalence of detected prostate cancer in the two populations, our data suggest that some 10.0% of Japanese-Americans aged 75 years have prostate cancer, with 31% of that fraction remaining undiagnosed. The corresponding estimates in Japan are a total cancer prevalence of 5.4%, of which 81% has not been detected clinically.

CONCLUSIONS

The total cancer prevalence ratio 10.0/5.4 = 1.9 (95% confidence interval = 1.5-2.3) in Japanese-American men compared with Japanese men in Japan suggests an increased risk for Japanese-American men, but of less magnitude than the fourfold to sixfold increase indicated by the incidence data.

Serum androgens and sex hormone-binding globulins in relation to lifestyle factors in older African-American, white, and Asian men in the United States and Canada

Differences in endogenous androgen levels have been hypothesized to explain ethnic differences in prostate cancer risk. To examine this hypothesis, we gathered data on serum concentrations of androgens and sex hormone-binding globulin (SHBG) in healthy older men from four ethnic groups at different levels of prostate cancer risk. As part of a population-based case-control study of prostate cancer we conducted in California, Hawaii, and Vancouver, Canada, 1127 African-American, white, Chinese-American, and Japanese-American control men, mostly ages 60 years or older (mean age, 69.9 years) provided information on various lifestyle factors and donated an early morning fasting blood sample between March 1990 and March 1992. We used these data to examine the distributions of serum androgens [testosterone (total, free, and bioavailable), dihydrotestosterone (DHT)], the ratio of DHT to total testosterone (DHT:testosterone ratio), and SHBG in these four ethnic groups. We also assessed correlations between concentrations of these measures with age, body size, physical activity, and other personal characteristics, and we evaluated ethnic differences in concentrations of androgens and SHBG after adjusting for these characteristics. In each of the four ethnic groups, concentrations of free and bioavailable testosterone declined with age, whereas SHBG concentrations increased with age. Age-adjusted concentrations of all androgen measures and SHBG decreased with increasing levels of Quetelet's index. After adjustment for age and Quetelet's index, androgens and SHBG showed no clear and consistent relationships to physical activity, alcohol consumption, or tobacco use. DHT:testosterone ratio was higher in men reporting a history of benign prostate disease than in men without such a history, and higher in vasectomized men than in nonvasectomized men. SHBG concentrations were higher in men reporting one or more first-degree relatives with prostate cancer than in men without such a family history. After adjustment for age and Quetelet's index, the levels of total and bioavailable testosterone were highest in Asian-Americans, intermediate in African-Americans, and lowest in whites. However, the DHT:testosterone ratio was highest in African-Americans, intermediate in whites, and lowest in Asian-Americans, corresponding to the respective incidence rates in these groups and providing indirect evidence for ethnic differences in 5alpha-reductase enzyme activity.

Vasectomy and prostate cancer: results from a multiethnic case-control study

BACKGROUND

Vasectomy, a widely used form of contraception, has been associated in some studies with increased prostate cancer risk.

PURPOSE

We assessed this association on the basis of data collected in a large multiethnic case-control study of prostate cancer that was conducted in the United States (Los Angeles, San Francisco, and Hawaii) and Canada (Toronto and Vancouver).

METHODS

In home interviews conducted with newly diagnosed prostate cancer case patients and population control subjects, we obtained information on the participants' medical history, including a history of vasectomy and the age at which the procedure was performed, as well as other potential risk factors. Blood samples were collected from control subjects only and were assayed for concentration of sex hormones and sex hormone-binding globulin.

RESULTS

The present analysis was based on 1642 prostate cancer patients and 1636 control subjects. A history of vasectomy was not significantly associated with prostate cancer risk among all racial/ethnic groups combined (odds ratio [OR] = 1.1; 95% confidence interval [CI] = 0.83-1.3), whites (OR = 0.94; 95% CI = 0.69-1.3), blacks (OR = 1.0; 95% CI = 0.59-1.8), or Chinese-Americans (OR = 0.96; 95% CI = 0.42-2.2). Among Japanese-Americans, the OR was 1.8 (95% CI = 0.97-3.4), but the statistically nonsignificant elevation in risk was limited to more educated men and those with localized cancers. ORs did not vary significantly by age at vasectomy or years since vasectomy. We found a lower serum concentration of sex hormone-binding globulin and a higher ratio of dihydrotestosterone to testosterone among vasectomized control subjects than among nonvasectomized control subjects.

CONCLUSIONS

The findings of this study do not support previous reports of increased prostate cancer risk associated with vasectomy. However, the altered endocrine profiles of vasectomized control subjects seen in this cross-sectional comparison warrant further evaluation in longitudinal studies.

Prostate cancer in relation to diet, physical activity, and body size in blacks, whites, and Asians in the United States and Canada

BACKGROUND

International and interethnic differences in prostate cancer incidence suggest an environmental, potentially modifiable etiology for the disease.

PURPOSE

We conducted a population-based case-control study of prostate cancer among blacks (very high risk), whites (high risk), and Asian-Americans (low risk) in Los Angeles, San Francisco, Hawaii, Vancouver, and Toronto. Our aim was to evaluate the roles of diet, physical activity patterns, body size, and migration characteristics on risk in these ethnic groups and to assess how much of the interethnic differences in risk might be attributed to interethnic differences in such lifestyle characteristics.

METHODS

We used a common protocol and questionnaire to administer personal interviews to 1655 black, white, Chinese-American, and Japanese-American case patients diagnosed during 1987-1991 with histologically confirmed prostate carcinoma and to 1645 population-based control subjects matched to case patients by age, ethnicity, and region of residence. Sera collected from 1127 control subjects were analyzed for levels of prostate-specific antigen (PSA) to permit comparison of case patients with control subjects lacking serological evidence of prostate disease. Odds ratios were estimated using conditional logistic regression. We estimated the proportion of prostate cancer attributable to certain risk factors and the proportion of interethnic risk differences attributable to interethnic differences in risk-factor prevalence.

RESULTS

A positive statistically significant association of prostate cancer risk and total fat intake was found for all ethnic groups combined. This association was attributable to energy from saturated fats; after adjusting for saturated fat, risk was associated only weakly with monounsaturated fat and was unrelated to protein, carbohydrate, polyunsaturated fat, and total food energy. Saturated fat intake was associated with higher risks for Asian-Americans than for blacks and whites. In all ethnic groups combined, the risk tended to be higher when only case patients with advanced disease were compared with control subjects with normal PSA levels. Among foreign-born Asian-Americans, risk increased independently with years of residence in North America and with saturated fat intake. Crude estimates suggest that differences in saturated fat intake account for about 10% of black-white differences and about 15% of white-Asian-American differences in prostate cancer incidence. Risk was not consistently associated with intake of any micronutrients, body mass, or physical activity patterns.

CONCLUSIONS

These data support a causal role in prostate cancer for saturated fat intake but suggest that other factors are largely responsible for interethnic differences in risk.

Family history and prostate cancer risk in black, white, and Asian men in the United States and Canada

Increased risk of prostate cancer in men with a family history of the disease has been observed consistently in epidemiologic studies. However, most studies have been confined to white men; little is known about familial aggregation of prostate cancer in populations with unusually high incidence, such as African Americans, or in populations with low incidence, such as Asian-Americans. The authors report results from a population-based case-control study of prostate cancer among blacks, whites, and Asian-Americans in the United States and Canada. Controls were matched to cases on age (5-year groups), ethnicity (black, white, Chinese-American, Japanese-American), and region of residence (Los Angeles, San Francisco, Hawaii, Vancouver, Toronto). In the combined group of participants, 5% of controls and 13% of cases reported a father, brother, or son with prostate cancer. These prevalences were somewhat lower among Asian-Americans than among blacks or whites. A positive family history was associated with a statistically significant two- to threefold increase in risk in each of the three ethnic groups. The overall odds ratio associated with such a family history, adjusted for age and ethnicity, was 2.5 (95% confidence interval 1.9-3.3). This odds ratio varied by neither ethnicity nor age of the participants. Sera from 1,087 controls were used to examine the relations between family history and serum concentrations of androgens and prostate-specific antigen. The concentrations of sex hormone-binding globulin were slightly higher in men with than without a positive family history. Prostate-specific antigen concentrations were unrelated to family history.

Effect of a monetary incentive on response to a mail survey

We assessed the effect of a $1 incentive on response to a two-page questionnaire which was sent to 8356 female cosmetologists between 22 and 36 years old. The study population was randomly assigned to one of three groups in which a $1 incentive was enclosed with either the first or second mailing, or with none of the mailings. Ten percent of questionnaires were returned by the postal service because of an incorrect address or death of the addressee and were omitted from response calculations. Of the remaining questionnaires, 79% were completed and returned after up to three mailings. The cumulative response was highest among cosmetologists who received a $1 incentive with the first mailing, (81%; 95% confidence interval (CI), 80 to 82), intermediate among those who received $1 with the second mailing (78%, 95% CI, 77 to 79), and lowest among cosmetologists who received no incentive (74%; 95% CI, 70 to 78). Characteristics of cosmetologists who responded after having received a "41 incentive were similar to those who responded without having received an incentive. The higher costs per response incurred by the use of an incentive must be weighed against the benefit of higher response.

Spontaneous abortions among cosmetologists

To examine the relation between adverse pregnancy outcomes and work in cosmetology during pregnancy, we conducted a mail survey in North Carolina among 8,356 licensed female cosmetologists 22-36 years of age. We identified pregnancies between 1983 and 1988 by a brief screening questionnaire, followed by a more detailed mail questionnaire. Seventy-four per cent of eligible cosmetologists responded to each inquiry. We restricted the main analysis to 96 cosmetologists with a spontaneous abortion and 547 cosmetologists with a single livebirth who worked full-time in cosmetology or in other jobs during the first trimester of pregnancy. With adjusted odds ratios ranging from 1.4 to 2.0, we found associations between spontaneous abortion and the number of hours worked per day in cosmetology, the number of chemical services performed per week, the use of formaldehyde-based disinfectants, and work in salons where nail sculpturing was performed by other employees. We found no important associations among full-time cosmetologists who performed few chemical services and among cosmetologists who worked less than 35 hours per week.

Characteristics relating to ovarian cancer risk: collaborative analysis of seven U.S. case-control studies. Epithelial ovarian cancer in black women. Collaborative Ovarian Cancer Group

BACKGROUND

Previous epidemiologic studies of ovarian cancer have focused chiefly on White women, who have a higher incidence of ovarian cancer than Black women. No study has previously examined risk factors for ovarian cancer among Black women.

PURPOSE

This study was designed to evaluate the risk of epithelial ovarian cancer in Black women in relation to reproductive characteristics such as pregnancy, oral contraceptive use, and breast-feeding, and to determine whether differences in reproductive factors between Black and White women account for differences in ovarian cancer incidence.

METHODS

Combining interview data from seven case-control studies, we compared reproductive characteristics of 110 Black case subjects with a diagnosis of epithelial ovarian cancer between 1971 and 1986 with characteristics of 251 Black population control subjects and 114 Black hospital control subjects. We also compared the prevalence of reproductive factors in 246 Black population control subjects and 4378 White population control subjects and estimated the fraction of Black-White differences in ovarian cancer incidence attributable to racial differences in prevalence of these characteristics.

RESULTS

Decreased risks of epithelial ovarian cancer in Black women were associated with parity of four or higher (odds ratio [OR] = 0.53; 95% confidence interval [CI] = 0.25-1.1), breast-feeding for 6 months or longer (OR = 0.85; 95% CI = 0.36-2.0), and use of oral contraceptives for 6 years or longer (OR = 0.62; 95% CI = 0.24-1.6). A greater proportion of Black women (48%) than White women (27%) reported four or more term pregnancies, and Black women (62%) were more likely than White women (53%) to have breast-fed their children. Oral contraceptive use was more common among White women (59%) than Black women (51%).

CONCLUSION

Differences in the prevalence of other factors related to ovarian cancer risk or differences in genetic susceptibility must explain most of the Black-White differences in incidence of ovarian cancer.

Use of NHANES data to assign nutrient densities to food groups in a multiethnic diet history questionnaire

In epidemiological studies of diet and chronic disease, a brief yet comprehensive diet history questionnaire must aggregate some foods into food groups. A nutrient density is assigned to each food group by averaging the densities of its constituent foods. A person's intake of a given nutrient is then estimated by multiplying the reported consumption of each food group by its average nutrient density and summing over food groups. These calculations could introduce bias in multiethnic studies, if the average nutrient densities assigned to food groups are inappropriate for some ethnic populations. This issue is examined here for intakes of total fat, saturated fat, and vitamin A for U.S. blacks and whites. We used 24-hour diet recall data from the Second National Health and Nutrition Examination Survey (NHANES II) to assess black-white differences in relative frequency of consumption of foods within food groups of a diet history questionnaire. We also calculated ethnic-specific average nutrient densities for each food group by weighting the densities of its foods in proportion to their frequency of consumption by black and white NHANES II participants. We found black-white differences in the frequency of consumption of foods within 14 food groups. However, blacks and whites had different average total fat densities for only 1 of the 14 food groups, no difference in saturated fat densities for any food group, and different vitamin A densities for 2 food groups. Among blacks and whites, there is no advantage to calculating ethnic-specific average nutrient densities for food groups comprised of foods with similar densities.(ABSTRACT TRUNCATED AT 250 WORDS)

Recent etiologic hypotheses concerning breast cancer

A few studies have noted moderate elevation in the risk of breast cancer among women with residential exposure to electromagnetic fields, among women without a history of much strenuous physical activity, and among women with in utero exposures that may indicate high levels of maternal estrogen. The relative risk for each of these associations has generally been less than 2, with little adjustment for possible confounding factors. Also, several studies have not been able to confirm these relations. Currently there is scant or no evidence that silicone breast implants or psychological factors increase the risk of breast cancer. Despite the limited number of studies, the inconsistent results, and the difficulty of measuring several of these exposures, the plausible biologic mechanisms for each indicate that more research on these hypotheses is warranted.

Association of paternal alcohol use with gestational age and birth weight

Paternal alcohol use has been associated with a number of adverse reproductive outcomes in laboratory animals and there is one epidemiologic report of a detrimental effect on infant birth weight. To expand the epidemiologic evidence, data from the Child Health and Development Studies were analyzed. Data collected from the onset of prenatal care in 10,232 women enrolled in the Kaiser Foundation Health Plan and residing in the San Francisco East Bay area between June 1959 and September 1966 were available, including information on the mother's report of paternal alcohol consumption and a number of potential confounders. Pregnancy outcomes included preterm delivery (< 37 weeks completed gestation), moderately low birth weight (1,501-2,500 g), very low birth weight (< or = 1,500 g), small-for-gestational-age (< 10th percentile of weight for gestational age), and mean birth weight. Paternal alcohol use, analyzed in intervals from 0 to 2.0 or more drinks per day, showed no association with any of the outcomes of interest. Adjusted prevalence odds ratios ranged from 0.7 to 1.5, with no indication of a monotonic dose-response gradient. Mean birth weight was also virtually unrelated to paternal alcohol use. Compared with the earlier report, this population had a very modest level of alcohol consumption. Nonetheless, within the range that was studied there appears to be no association between paternal alcohol use and birth outcome.

Use of a job-exposure matrix to evaluate parental occupation and childhood cancer

We examined the association between parental occupation and childhood cancer among 252 incident cases of childhood cancer (ages 0-14, diagnosed 1976-83) and 222 controls selected by random digit dialing in Denver, Colorado (USA). A job-exposure matrix was used to assign parental exposures based on job titles, emphasizing chemicals that were implicated in previous studies. All cancers, acute lymphocytic leukemia (ALL), and brain cancer were examined in relation to parental occupation during the year prior to the birth of the child. Elevated odds ratios (OR), all with confidence intervals extending below the null, were found for maternal exposure to benzene (OR = 1.9), petroleum/coke pitch/tar (OR = 2.2), and soot (OR = 3.3) in relation to total cancers. The ORs for total cancer and paternal exposure to all hydrocarbons combined was 1.0. Results for individual hydrocarbons and ALL showed larger odds ratios, including aniline (OR = 2.1), benzene (OR = 1.6), and petroleum/coke pitch/tar (OR = 1.6). Potential exposure to creosote was strongly associated with brain cancer (OR = 3.7) based on five exposed cases (95 percent confidence interval = 0.8-16.6). Control for other potential childhood cancer risk factors did not alter the results substantially. In spite of uncertainties due to small numbers and errors in exposure classification, results tend to corroborate past research that suggests an association between specific parental occupational exposures and childhood cancer.

Prenatal exposure to parents' smoking and childhood cancer

The relation between parents' tobacco smoking prior to birth and cancer in the offspring was investigated with the use of data from a case-control study. Incident cases included all children (aged 0-14 years) diagnosed in Denver, Colorado from 1976 to 1983. Controls were selected through random digit dialing, and matched to cases on age, sex, and geographic area. Information on smoking by parents and other household members was obtained by personal interview for 223 cases and 196 controls. After adjustment for father's education, mother's smoking during the first trimester of pregnancy was associated with an increased risk for all cancers combined (odds ratio (OR) = 1.3, 95% confidence interval (CI) 0.7-2.1), acute lymphocytic leukemia (OR = 1.9, 95% CI 0.9-4.1), and lymphomas (OR = 2.3, 95% CI 0.8-7.1). Adjusting for father's education, associations with father's smoking in the absence of mother's smoking were found for all cancers combined (OR = 1.2, 95% CI 0.8-2.1), acute lymphocytic leukemia (OR = 1.4, 95% CI 0.6-3.1), lymphomas (OR = 1.6, 95% 0.5-5.4), and brain cancer (OR = 1.6, 95% CI 0.7-3.5). In spite of imprecision resulting from small numbers of cases in diagnostic subgroups, these results are suggestive of a possible influence of parents' smoking on childhood cancer.

Magnetic field exposure from electric appliances and childhood cancer

The effect on childhood cancer of prolonged exposure to 60-H magnetic fields from electric appliances was examined using interview data from a recently completed case-control study. Exposures of children aged 0-14 years whose incident cancers were diagnosed between 1976 and 1983 and who resided in the Denver, Colorado, Standard Metropolitan Statistical Area were compared with those of controls selected by random digit dialing, matched on age, sex, and telephone exchange area. Parents of 252 cases and 222 controls were interviewed at home about the use of electric appliances by the mother during pregnancy (prenatal exposure) and by the child (postnatal exposure). After adjustment for income, prenatal electric blanket exposure was associated with a small increase in the incidence of childhood cancers (odds ratio (OR) = 1.3, 95% confidence interval (CI) 0.7-2.2) that was more pronounced for leukemia (OR = 1.7, 95% CI 0.8-3.6) and brain cancer (OR = 2.5, 95% CI 1.1-5.5). Postnatal exposure to electric blankets was also weakly associated with childhood cancer (OR = 1.5, 95% CI 0.6-3.4), with a larger but imprecise association with acute lymphocytic leukemia (OR = 1.9, 95% CI 0.6-6.5). Water beds and bedside electric clocks were unrelated to childhood cancer incidence. Results are limited by nonresponse and imprecision resulting from the rarity of appliance use, especially for subgroups of cases. Nonetheless, electric blankets, one of the principal sources of prolonged magnetic field exposure, were weakly associated with childhood cancer and warrant a more thorough evaluation.

Case-control study of childhood cancer and exposure to 60-Hz magnetic fields

Concern with health effects of extremely low frequency magnetic fields has been raised by epidemiologic studies of childhood cancer in relation to proximity to electric power distribution lines. This case-control study was designed to assess the relation between residential exposure to magnetic fields and the development of childhood cancer. Eligible cases consisted of all 356 residents of the five-county 1970 Denver, Colorado Standard Metropolitan Statistical Area aged 0-14 years who were diagnosed with any form of cancer between 1976 and 1983. Controls were selected by random digit dialing to approximate the case distribution by age, sex, and telephone exchange area. Exposure was characterized through in-home electric and magnetic field measurements under low and high power use conditions and wire configuration codes, a surrogate measure of long-term magnetic field levels. Measured magnetic fields under low power use conditions had a modest association with cancer incidence; a cutoff score of 2.0 milligauss resulted in an odds ratio of 1.4 (95% confidence interval (CI) = 0.6-2.9) for total cancers and somewhat larger odds ratios (ORs) for leukemias (OR = 1.9), lymphomas (OR = 2.2), and soft tissue sarcomas (OR = 3.3). Neither magnetic fields (OR = 1.0) nor electric fields (OR = 0.9) under high power use conditions were related to total cancers. Wire codes associated with higher magnetic fields were more common among case than control homes. The odds ratio to contrast very high and high to very low, low, and buried wire codes was 1.5 (95% CI = 1.0-2.3) for total cases, with consistency across cancer subgroups except for brain cancer (OR = 2.0) and lymphomas (OR = 0.8). Contrasts of very high to buried wire code homes produced larger, less precise odds ratios of 2.3 for total cases, 2.9 for leukemias, and 3.3 for lymphomas. Adjusted estimates for measured fields and wire codes did not differ from crude results, indicating an absence of confounding. Limitations to the study are nonresponse (especially for field measurements), differential mobility of cases and controls, and a presumably nondifferential exposure misclassification from the use of imperfect surrogates for long-term magnetic field exposure history. In spite of these concerns, the results encourage further examination of the carcinogenic potential from this form of nonionizing radiation.

Imino proton assignments in the proton nuclear magnetic resonance spectrum of the lambda phage OR3 deoxyribonucleic acid fragment

The 17 base pair duplex d(TATCACCGCAAGGGATAp) . d(TATCCCTTGCGGTGATAp) corresponding to the OR3 operator site of lambda phage has been synthesized and studied by 1H nuclear magnetic resonance spectroscopy at 470 MHz. The 13 imino proton resonances observed at 20 degrees C have been assigned to specific base pairs at positions 3-15 on the basis of nuclear Overhauser effect measurements and studies of the temperature dependence of peak intensities. Resonances from the A-T base pairs at positions 1, 2, 16, and 17 are assumed to be absent from the spectrum because of terminal fraying. Resonance from many of the base pairs suggested by Ohlendorf et al. [Ohlendorf, D. H., Anderson, W. F., Fisher, R. G., Takeda, Y., & Matthews, B. W. (1982) Nature (London) 298, 718-723] to be involved in specific binding of the lambda phage cro repressor are well resolved.

Stoichiometry of oxygen consumption in the biosynthesis of isopenicillin from a tripeptide

The biosynthesis of isopenicillin N from delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine in a cell-free system has been correlated wih O2 consumption by two methods, involving the use of an oxygen-electrode and an n.m.r. spectrometer respectively. The results are consistent with a 1 : 1 stoichiometric ratio for the dioxygen consumed to the isopenicillin N formed.